1. Field of the Invention
The present invention relates to a storage system, a virtualization method, and a storage apparatus, and is particularly suitable for a storage apparatus having external connectability, and a storage system having the storage apparatus as a component.
2. Description of Related Art
As disclosed in JP-A-2005-157867, a conventional storage apparatus has, as one of its functional capabilities, external connectability that can virtualize logical volumes (logical volumes are units of storage areas, and they are conventionally referred to as “logical devices” in mainframe systems) provided by each of one or more other storage apparatuses connected to that storage apparatus.
In these cases, in a storage apparatus (hereinafter, referred to as “internal storage apparatus”) that virtualizes another storage apparatus, virtual logical volumes (hereinafter, referred to as “virtual volumes”) are configured in association with logical volumes defined in the virtualized storage apparatus (hereinafter, referred to as “external storage apparatus”).
The internal storage apparatus, upon receipt of a request from a host apparatus to access a virtual volume, transfers the access request to the external storage apparatus that has the corresponding logical volume, and has the external storage apparatus execute the actual data input/output processing.
The aforementioned external connectability makes it possible to collectively manage the logical volumes provided by a plurality of storage apparatuses, facilitating easy addition of a storage apparatus or similar.